1. Field of the Invention
The present invention generally relates to a field synchronization system and technique and more specifically, to a field synchronization system and technique of a field detect circuit adaptable for use with non-standard output digital data ports of forward looking infrared (FLIR) sensors.
2. Description of Prior Art
Television is the transmission of scenes, either still or in motion, by electrical means. It is necessary to break up the scene into minute elements and utilize these elements in an orderly sequence. This process is called scanning, a type of which is somewhat similar to the process of reading a text line-by-line (or row of data) from a printed page (called interlacing). Because of the physical principles involved, there is a relationship between brightness and the rate of scanning: brightness going down with increase scanning rate. To provide a true and realistic feeling of motion to all actions displayed, it is necessary to present a number of pictures or frames per second. Early designers in compromising on brightness, utilized a reasonable transmission bandwidth, and frame frequency, selected a rate of display of 30 complete pictures per second. A frame frequency of only 30 pictures/second would result in a flicker discernible to the eye, so each picture is divided into two parts called fields. Two fields must be produced in order to make one complete picture or frame. The field frequency is therefore 60 fields/second and the frame frequency is 30 frames/second. Each field contains one-half of the total picture elements.
For a decernible picture to be presented, there requires a digital timing protocol for the differentiation and synchronization of the two fields into one interlaced frame of digital information that is utilized by a field detect circuitry. A problem occurs in the prior art when the digital data inputs to the field circuitry does not follow the SMPTE Standard 244M known in the Prior Art. Many FLIR sensors output their own field index but do not follow the accepted protocol with respect to the falling edges of the horizontal and vertical synchronization signals. While the prior art has reported using field detect circuits, none have established a basis for a specific apparatus that is dedicated to the task of resolving the particular problem at hand. What is needed in this instance is a field synchronization system and technique of a field detect circuit adaptable for use with non-standard output digital data ports of forward looking infrared (FLIR) sensors.